On resistance (Ron) flatness is a concern in analog switches and one way to achieve a flatter Ron is by allowing the back-gate of the NMOS transistor to increase in voltage, producing a stronger transistor with less resistance. To allow the back-gate to rise an NMOS transistor is used as a switch to connect and disconnect the back-gate to its source. The drawback with this is during a power down condition the back-gate will be left floating and will allow higher leakage through the pass transistor.